1 / 24

Defficiency states of

Defficiency states of. VITAMIN D. dr mukesh kumar. What is Vitamin D?. Vitamin D is a fat-soluble pro-hormone Sterol derivative 2 forms of vitamin D Vitamin D2 (Ergocalciferol) Vitamin D3 (Cholecalciferol) Pro-hormone is converted into its biologically active metabolite: calcitriol

charo
Download Presentation

Defficiency states of

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Defficiency states of VITAMIN D dr mukesh kumar

  2. What is Vitamin D? Vitamin D is a fat-soluble pro-hormone Sterol derivative 2 forms of vitamin D Vitamin D2 (Ergocalciferol) Vitamin D3 (Cholecalciferol) Pro-hormone is converted into its biologically active metabolite: calcitriol Vitamin D may be obtained from the diet and through skin exposure to sunlight (UV light)

  3. Uses for Vitamin D Maintains structural integrity of bones & bone growth by regulating use of calcium + phosphate (bone turnover) Maintains serum calcium homeostasis Research shows that Vitamin D may play a role in immune function and protection from chronic diseases

  4. Synthesis and Metabolism Ergocalciferol (D2) synthesized in plant and fungi when ergosterol undergoes photolysis under UV light Cholecalciferol (D3) synthesized in skin of animals by photolysis of 7-dehydrocholesterol Bioactivation occurs through 2 steps Hydroxylation in liver produces calcidiol Hydroxylation in kidney produces calcitriol

  5. Mechanism of Action Calcitriol is transported through the circulatory system by vitamin D binding protein and albumin Diffuses into the nucleus of target cells and binds to Vitamin D receptor (VDR) VDR associates with Retinoic Acid X receptor (RXR) – forms VDR-RXR complex VDR-RXR binds to DNA sequences called Vitamin D Response Elements (VDREs) to modulate the expression of >50 genes

  6. Mechanism of Action VDRE regulated gene expression leads to: Increased dietary calcium and phosphorus absorption in small intestine Increased renal reabsorption of calcium Increased renal excretion of phosphate Increased resorption of bone to increase serum calcium levels

  7. Sources of Vitamin D- Food Less than 10%! Natural Food Sources: Egg Yolk 20-25/yolk Shrimp 152/100gm Tuna 224-332/100gm Canned salmon 624/100gm Fortified Food Sources: Vitamin D milk 400/L Formula 400/L Cereal 40/serving Yogurt 89/100gm

  8. Sources of Vitamin D - Sun UV light converts cholesterol in skin into D3 Dark skinned people require a longer duration of sun exposure for adequate production of Vitamin D Less UV light is available in the winter months, higher latitudes, and with cloud cover and air pollution

  9. Vitamin D sources Fortified foods (milk and orange juice) Fish liver oil Cod liver oil contains over 1000IU/tablespoon Fatty fish (salmon, tuna) Liver, beef Sunlight exposure 5-30 minutes in direct sunlight at mid-day Supplements

  10. Recommended Dietary Allowances *Adequate intake rather then RDA Retrieved from Health Canada. (2010, December 13). Vitamin D and Calcium: Updated Dietary Reference Index

  11. Why do breast fed babies need supplemental Vitamin D? Breast milk contains little vitamin D • 25-78 IU/day • Rates of vitamin D deficiency in breastfed infants up to 78% in winter Limited sun exposure : infants less than 6 months should be kept out of direct sunlight

  12. Why do breast fed babies need supplemental Vitamin D? High rates of Vitamin D maternal deficiency • Pittsburgh study at birth: • Black women • 29% deficient • 54% insufficient • White women • 5% deficient • 42% insufficient

  13. Preventing Vitamin D deficiency • Breastfed and partially breastfed infants should be supplemented with 400 IU/day of vitamin D beginning in the first few days of life. • Supplementation should be continued unless the infants is weaned to at least 1L/day of vitamin D-fortified formula or fortified milk. TriViSol contains 400 IU per ml

  14. Vitamin D Deficient States • Rickets • Peak incidence 3-18 months • Defective bone growth due to lack of mineralization at growth plate • Hypocalcemic seizures • Growth failure, lethargy, irritability • Delay in gross motor development, bone pain

  15. Vitamin D Deficient states Rickets Bowing or widening of physis Costochondral beading (rachitic rosary) Craniotabes Delayed closure of anterior fontanel Dental abnormalities Flaring of ribs at diaphragm

  16. Vitamin D Deficiency Inadequate exposure to sunlight (UV rays) Inadequate intake from diet Deficiencies in GI tract absorption Kidney or liver disorders Retrieved from: http://emedicine.medscape.com/article/412862-overview

  17. Rickets (children) Pathophysiology Rickets is failure of bone to mineralize Growth plates of bone continue to enlarge while the load on the limbs continues to increase In the absence of mineralization, limbs become bowed Symptoms Characterized by stunted growth and deformed bones In infants, rickets may result in the delayed closure of fontanelles (soft spots on baby’s head)

  18. Treatment • Vitamin D and calcium supplements • Corrective surgery or bracing for skeletal deformities

  19. Vitamin D Deficient States • Adult Vitamin D deficiency implicated in • Increased infections • Autoimmune diseases (Multiple Sclerosis, Rheumatoid arthritis) • Cancer • Type 2 Diabetes • Bipolar disorder, schizophrenia • Type I Diabetes in childhood • Maternal Vitamin D status associated with adverse outcomes of pregnancy – miscarriage, preeclampsia, preterm birth

  20. Osteomalacia (adult) Pathophysiology Impaired bone mineralization Adult bones are in constant state of turnover and new bones are brittle and thin Symptoms Bone pain (lower spine, pelvis, hips, legs, ribs) May result in muscle weakness Treatment Vitamin D supplements Treating conditions affecting vitamin D absorption and metabolism

  21. Osteoporosis Pathophysiology Rate of bone loss is greater than rate of bone formation – gradual loss of bone mass Bone strength is compromised – increased risk of fracture Symptoms Non-specific chronic back pain Height loss Bone fractures occur more easily

  22. Treatment and Prevention • Maximizing/maintaining existing bone mass density • Calcium and vitamin D supplements, weight-bearing exercise • Minimize risk of falls

  23. Laboratory diagnosis Vitamin D status- 25(OH)-D levels • Deficiency <37.5 nmol/mL • Insufficiency 37.5-50 nmol/mL • Sufficiency >50 (?) nmol/mL Severe deficiency states associated with: Ca,PO4, Alk Phos, PTH

  24. Summary Slide Vitamin D (fat-soluble, pro-hormone): ergocalciferol (D2) and cholecalciferol (D3) • converted to active hormonal form, calcitriol by metabolism in liver and kidney • Targets: bone, kidney and GI tract • Function: maintains serum calcium levels & integrity of bones growth via calcium regulation Deficiency – leads to rickets, osteomalacia and osteoporosis • Lack of calcium leads to impaired bone mineralization and loss of bone mass • Treatment: Increase vitamin D and calcium intake, and increase bone mass density

More Related